A separating agent obtained by carrying a polysaccharide derivative on silica gel has been generally used as, for example, an enantiomeric resolution agent for high performance liquid chromatography. The manners in which the silica gel supports the polysaccharide derivative are classified into the case where silica gel is caused to support the polysaccharide derivative physically (physical support type separating agent) and the case where silica gel is caused to support the polysaccharide derivative by chemical bonding (chemical support type separating agent). See JP-B-2751004 or JP-A-8-5623.
The chemical support type separating agent has a smaller amount of eluted component originating from the polysaccharide derivative than that of the physical support type separating agent, even when an organic solvent in which the polysaccharide derivative is soluble is used. However, an unreacted polysaccharide derivative is present, even in the chemical support type separating agent, so an eluent contains an eluted component originating from the polysaccharide derivative.
In the case where an eluted component originating from, for example, an unreacted polysaccharide derivative is present in an eluent as described above, the following problem arises depending on whether the amount of eluted component is large or small when a separating agent containing the eluted component is used as a separating agent for high performance liquid chromatography: the stability of the baseline of a chromatogram deteriorates, or the purity of a fractionated product cannot be sufficiently increased.
Investigations have already been conducted on a method reducing the amount of eluted component in the physical support type separating agent. JP-A 7-260762 discloses a coating type separating agent having a small amount of eluted component.